It is desirable to foam (i.e. to aerate to a froth by the trapping of air pockets) beverages or foodstuffs, or components thereof, during beverage preparation. One example is milk that is foamed with coffee added thereto to form a latté or a cappuccino. A further example is the whisking of egg whites or cream to a mousse.
Accordingly various appliances exist to automate a foaming process. An example of one such appliance is disclosed in WO 2006/050900, wherein a container for containing a liquid to be foamed has arranged therein a rotary agitator which is rotated for said foaming. In particular, the rotary agitator is part of an agitation system that further comprises: permanent agitator magnets incorporated on the rotary agitator; permanent drive magnets arranged external the container; a rotor operable to rotate said drive magnets, whereby rotation of the drive magnets effects a rotating magnetic field to transmit torque to the agitator magnets.
In particular the rotor is driven by an electrically operated motor, which is arranged beneath the container. A drawback with such an arrangement is that the housing of the appliance has to house said motor and the drive magnets, both of which are bulky and impose size constraints on the housing, which is undesirable for reasons material wastage and economy of space on a worktop. A further drawback is that said drive magnets are limited in the amount of torque they can apply to the whisk by virtue of their degree of magnetisation.